When they ban the "extremists" the "moderates" thrive making youtube/reddit/etc posts about the obvious double standards, and the impossible to pass purity tests created to ban those "extremists". The logical inconsistency of both sides of the current "culture" war parties in the US create a near unending supply of "gotcha" moments, which are just fuel for the fire.
If anything, banning extremists makes these ideologies more palatable to a larger group of people by creating a more gradual on-ramp at the entry level. I believe this is becoming more obvious as we see the middle ground position in the current "culture" conflict (which would still probably get you banned from facebook) rapidly becoming acceptable. The pendulum keeps swinging, and not many people involved seem very interested in stopping the broken cycle and finding a more sustainable solution.
If anything, banning extremists makes these ideologies more palatable to a larger group of people by creating a more gradual on-ramp at the entry level. I believe this is becoming more obvious as we see the middle ground position in the current "culture" conflict (which would still probably get you banned from facebook) rapidly becoming acceptable. The pendulum keeps swinging, and not many people involved seem very interested in stopping the broken cycle and finding a more sustainable solution.